Battery-powered system, battery pack, electric work machine, and charger

ABSTRACT

A battery-powered system includes a battery pack (10; 71; 81) connected to an electrical equipment (30; 50; 76; 86). The battery pack includes a first positive electrode terminal (11), a first negative electrode terminal (12), a first communication terminal (13), a first data input circuit (23), and a first limiting circuit (D11; D72; D82) that limits a flow of electric current in a direction from the first negative electrode terminal to the first communication terminal via the first data input circuit. The connected equipment includes a second positive electrode terminal (31; 51), a second negative electrode terminal (32; 52), a second communication terminal (33; 53), a second data input circuit (43; 63; 77; 87), and a second limiting circuit (D31; D51; D77; D87) that limits a flow of electric current in a direction from the second negative electrode terminal to the second communication terminal via the second data input circuit.

CROSS-REFERENCE

This application claims priority to Japanese patent application serialnumber 2019-104453, filed on Jun. 4, 2019, the contents of which areincorporated herein by reference in their entirety.

TECHNICAL FIELD

The present disclosure generally relates to circuit designs forexecuting data communication between a battery pack and an electricalequipment/device, such as an electric work machine (e.g., a power tool),a charger, etc., that is electrically connected to the battery pack.

BACKGROUND ART

Japanese Laid open Publication 2017-140686 discloses a power tool systemconfigured to perform serial communication between a battery pack, whichcomprises a battery, and a power tool.

In this known power tool system, the battery pack comprises a negativeelectrode terminal, which is connected to a negative electrode of thebattery, and a communication terminal. The power tool comprises anegative electrode terminal, which is connected to the negativeelectrode terminal of the battery pack, and a communication terminal,which is connected to the communication terminal of the battery pack.The serial communication between the battery pack and the power tool isperformed via these communication terminals.

SUMMARY OF THE INVENTION

The power tool system disclosed in Japanese Laid open Publication2017-140686 has a closed loop that includes the negative electrodeterminal and the communication terminal of the battery pack and thenegative electrode terminal and the communication terminal of the powertool. Therefore, it is possible for unintended (undesirable) noisecurrents to flow in this closed loop owing to, for example, noisegenerated in the power tool when the motor is driven or various otherfactors.

If a sufficiently high noise current (noise voltage) flows in thisclosed loop, then there is a possibility that a data receiving processwill be erroneously executed (performed) in the power tool or thebattery pack due to this noise current degrading the signal integrity ofa signal transmitted from the battery pack to the power tool or viceversa. In this case, it is not possible to receive data accurately.

Therefore, it is one non-limiting object of the present disclosure toimprove the accuracy of data communication between a battery pack and anelectrical equipment connected thereto, even if noise is generated(present) in the communication circuit.

In one non-limiting aspect of the present disclosure, abattery-connected system (alternatively, “battery-powered system”) maycomprise a battery pack and a connected equipment (in particular, anelectrical equipment/device, such as an electric work machine (e.g., apower tool), a charger, etc.). The connected equipment isadapted/configured to be selectively placed in a connected state, inwhich the connected equipment has been electrically connected to thebattery pack, and in a state, in which the connected state has beenreleased (terminated).

The battery pack may comprise at least a battery, a first positiveelectrode terminal, a first negative electrode terminal, a firstcommunication terminal, a first data output circuit, a first data inputcircuit, and a first noise current limiting circuit or a first reversecurrent protection circuit (hereinafter, simply “first limitingcircuit”). The battery comprises a positive electrode and a negativeelectrode. The first positive electrode terminal is electricallyconnected to the positive electrode of the battery. The first negativeelectrode terminal is electrically connected to the negative electrodeof the battery. The first data output circuit may comprise at least afirst output terminal, which is electrically connected to the firstcommunication terminal, and is adapted/configured to output firsttransmit-data (one or more signals containing data regarding thebattery, such as, e.g., current voltage, current temperature, etc.) fromthe first output terminal. The first data input circuit may comprise atleast a first input terminal, which is electrically connected to thefirst communication terminal, and a first ground terminal, which iselectrically connected to the first negative electrode terminal, and isadapted/configured such that second transmit-data (one or more signalscontaining data and/or instructions output by the connected equipment),which has been input (transmitted) from the connected equipment to thefirst communication terminal, is input to (at) the first input terminal.The first limiting circuit is adapted/configured to at least limit aflow of electric current (e.g., a noise current) in the direction fromthe first negative electrode terminal to the first communicationterminal via the first data input circuit. That is, the first limitingcircuit is preferably designed to at least limit the flow of electriccurrent (e.g., noise) in the direction that is opposite (reverse) of thedirection that the second-transmit data moves (flows) from the firstcommunication terminal to the first input terminal. The first limitingcircuit is preferably designed to not limit the flow of electric current(e.g., signals) in the direction that the second-transmit data moves(flows) from the first communication terminal to the first inputterminal.

The electric work machine may comprise at least a second positiveelectrode terminal, a second negative electrode terminal, a secondcommunication terminal, a second data output circuit, a second datainput circuit, and a second noise current limiting circuit or a secondreverse current protection circuit (hereinafter, simply “second limitingcircuit”). The second positive electrode terminal is adapted/configuredto be electrically connected to the first positive electrode of thebattery pack in response to the connected equipment entering theconnected state (e.g., when the battery pack is mounted on (physicallyand electrically connected to) the connected equipment). The secondnegative electrode terminal is adapted/configured to be electricallyconnected to the first negative electrode of the battery pack inresponse to the connected equipment entering the connected state. Thesecond communication terminal is adapted/configured to be electricallyconnected to the first communication terminal of the battery pack inresponse to the connected equipment entering the connected state. Thesecond data output circuit may comprise at least a second outputterminal, which is electrically connected to the second communicationterminal, and is adapted/configured to output second transmit-data (oneor more signals containing data/instructions generated and output by theconnected equipment) from the second output terminal. The second datainput circuit may comprise at least a second input terminal, which iselectrically connected to the second communication terminal, and asecond ground terminal, which is electrically connected to the secondnegative electrode terminal, and is adapted/configured such that thefirst transmit-data, which has been input (transmitted) from the batterypack to the second communication terminal, is input to (at) the secondinput terminal. The second limiting circuit is adapted/configured to atleast limit a flow of electric current in the direction from the secondnegative electrode terminal to the second communication terminal via thesecond data input circuit. That is, the second limiting circuit ispreferably designed to at least limit the flow of electric current(e.g., noise) in the direction that is opposite (reverse) of thedirection that the first-transmit data moves (flows) from the secondcommunication terminal to the second input terminal. The second limitingcircuit is preferably designed to not limit the flow of electric current(e.g., signals) in the direction that the first-transmit data moves(flows) from the second communication terminal to the second inputterminal.

With such an embodiment of a battery-connected system (orbattery-powered system; the same applied hereinbelow), because thebattery pack comprises the first limiting circuit, the flow of electriccurrent in the battery pack from the first data input circuit to thefirst communication terminal and, in turn, the input of that electriccurrent to the connected equipment is limited, e.g., below a level thatdoes not detrimentally affect the signal integrity of thesecond-transmit data. Furthermore, because the connected equipmentcomprises the second limiting circuit, the flow of electric current inthe connected equipment from the second data input circuit to the secondcommunication terminal and, in turn, the input of that electric currentto the battery pack is limited, e.g., below a level that does notdetrimentally affect the signal integrity of the first-transmit data.Consequently, such a design makes it possible to more accurately execute(perform) data communication between the battery pack and the connectedequipment.

In addition, the battery pack may include a first signal path connectingthe first input terminal and the first communication terminal. The firstsignal path may include a first connection point. By connecting thefirst output terminal to the first connection point, the first outputterminal is electrically connected to the first communication terminalvia the first connection point and the first signal path. The firstlimiting circuit may be provided on the first data input circuit side ofthe first connection point.

With such an embodiment of a battery-connected system, because the firstlimiting circuit is provided in the battery pack on the first data inputcircuit side of the first connection point (i.e. the first limitingcircuit is not provided in the signal path connecting the firstcommunication terminal to the first output terminal in the batterypack), the first limiting circuit does not degrade (negatively affect)the quality (signal integrity) of the first transmit-data transmittedfrom the first data output circuit to the connected equipment via thefirst communication terminal.

In addition or in the alternative, the connected equipment may include asecond signal path connecting the second input terminal and the secondcommunication terminal. The second signal path may include a secondconnection point. By connecting the second output terminal to the secondconnection point, the second output terminal is electrically connectedto the second communication terminal via the second connection point andthe second signal path. The second limiting circuit may be provided onthe second data input circuit side of the second connection point.

With such an embodiment of a battery-connected system, because thesecond limiting circuit is provided in the connected equipment on thefirst data input circuit side of the second connection point (i.e. thesecond limiting circuit is not provided in the signal path connectingthe second communication terminal to the second output terminal in theconnected equipment), the second limiting circuit does not degrade(negatively affect) the quality (signal integrity) of the secondtransmit-data transmitted from the second data output circuit to thebattery pack via the second communication terminal.

In addition or in the alternative, the first data input circuit of thebattery pack may comprise at least a first switching device (e.g., atransistor), a first bias path, and a first resistor. The firstswitching device may comprise at least a first switch input terminal(e.g., a gate of the transistor), which is electrically connected to thefirst input terminal, and a first switch ground terminal (e.g., a sourceof the transistor), which is electrically connected to the first groundterminal. The first bias path may connect the first switch inputterminal and the first switch ground terminal (e.g., a gate-sourceconnection) and thus ultimately to the first ground terminal. The firstresistor may be provided in the first bias path. Furthermore, the firstlimiting circuit may be provided in the first bias path.

With such an embodiment of a battery-connected system, because the firstlimiting circuit is provided in the first bias path in the battery pack(i.e. the first limiting circuit is not provided in the signal pathconnecting the first communication terminal to the first switch inputterminal of the first data input circuit), the first limiting circuitdoes not degrade (negatively affect) the quality (signal integrity) ofthe second transmit-data output from the connected equipment and inputto the first data input circuit of the battery pack via the first andsecond communication terminals and the first input terminal.

In addition or in the alternative, the second data input circuit of theconnected equipment may comprise at least a second switching device(e.g., a transistor), a second bias path, and a second resistor. Thesecond switching device may comprise at least a second switch inputterminal (e.g., a gate of the transistor), which is electricallyconnected to the second input terminal, and a second switch groundterminal (e.g., a source of the transistor), which is electricallyconnected to the second ground terminal. The second bias path mayconnect the second switch input terminal and the second switch groundterminal (e.g., a gate-source connection) and thus ultimately to thesecond ground terminal. The second resistor may be provided in thesecond bias path. Furthermore, the second limiting circuit may beprovided in the second bias path.

With such an embodiment of a battery-connected system, because thesecond limiting circuit is provided in the second bias path in theconnected equipment (i.e. the second limiting circuit is not provided inthe signal path connecting the second communication terminal to thesecond switch input terminal of the second data input circuit), thesecond limiting circuit does not degrade (negatively affect) the quality(signal integrity) of the first transmit-data output from the batterypack and input to the second data input circuit of the connectedequipment via the first and second communication terminals and thesecond input terminal.

In addition or in the alternative, the first limiting circuit maycomprise at least a first diode that limits the flow of electric currentin the direction from the first negative electrode terminal to the firstcommunication terminal via the first data input circuit.

With such an embodiment of a battery-connected system, it is possible toconfigure the first limiting circuit in a simple manner.

In addition or in the alternative, the second limiting circuit maycomprise at least a second diode that limits the flow of the electriccurrent in the direction from the second negative electrode terminal tothe second communication terminal via the second data input circuit.

With such an embodiment of a battery-connected system, it is possible toconfigure the second limiting circuit in a simple manner.

In addition or in the alternative, the connected equipment may comprisea mounting part, which is adapted/configured such that the battery packis mountable thereon and demountable (removable, detachable) therefrom.The connected equipment may be adapted/configured to be placed in theconnected state in response to the battery pack being mounted on themounting part.

With such an embodiment of a battery-connected system, it is possible tomechanically and electrically connect the battery pack and the connectedequipment in a simple manner.

The battery-connected system may further comprise an intermediate device(e.g., a corded adapter). The intermediate device may comprise at least:a cable (cord); a first mounting part, which is adapted/configured suchthat the battery pack is mountable thereon and demountable therefrom;and a second mounting part, which is adapted/configured such that theconnected equipment is mountable thereon and demountable therefrom.

The first mounting part may comprise at least a first positive electrodeintermediate terminal, a first negative electrode intermediate terminal,and a first communication intermediate terminal. The first positiveelectrode intermediate terminal may be adapted/configured to beconnected to the first positive electrode terminal in response to thebattery pack being mounted on the first mounting part. The firstnegative electrode intermediate terminal may be adapted/configured to beconnected to the first negative electrode terminal in response to thebattery pack being mounted on the first mounting part. The firstcommunication intermediate terminal may be adapted/configured to beconnected to the first communication terminal in response to the batterypack being mounted on the first mounting part.

The second mounting part may comprise at least a second positiveelectrode intermediate terminal, a second negative electrodeintermediate terminal, and a second communication intermediate terminal.The second positive electrode intermediate terminal may beadapted/configured to be connected to the second positive electrodeterminal in response to the connected equipment being mounted on thesecond mounting part. The second negative electrode intermediateterminal may be adapted/configured to be connected to the secondnegative electrode terminal in response to the connected equipment beingmounted on the second mounting part. The second communicationintermediate terminal may be adapted/configured to be connected to thesecond communication terminal in response to the connected equipmentbeing mounted on the second mounting part.

The cable may comprise (contain within it) at least a positive electrodeintermediate wire, a negative electrode intermediate wire, and acommunication intermediate wire. The positive electrode intermediatewire may electrically connect the first positive electrode intermediateterminal and the second positive electrode intermediate terminal. Thenegative electrode intermediate wire may electrically connect the firstnegative electrode intermediate terminal and the second negativeelectrode intermediate terminal. The communication intermediate wire mayelectrically connect the first communication intermediate terminal andthe second communication intermediate terminal.

With such an embodiment of a battery-connected system, because thebattery pack and the connected equipment are electrically connected viathe intermediate device without being directly connected in a mechanicalmanner, the ergonomics of the battery-connected system can be improvedowing to the fact that the battery pack (which may be heavy) may beplaced, e.g., on a surface, such as the ground or a table, or clipped toan article of clothing, e.g., a belt, a shoulder harness, etc., whilethe user holds the connected equipment to perform work with theconnected equipment (which does not have the weight of the battery packattached thereto), thereby reducing the load (strain) on the user whileperforming work with the connected equipment.

In addition or in the alternative, the connected equipment may compriseor may be an electric work machine, such as, e.g., a power tool, outdoorpower equipment, etc. The electric work machine may comprise amanipulatable switch (e.g., a trigger), a motor, a motor drive circuit(e.g., a PWM circuit), and a drive mechanism (e.g., a geartransmission). The manipulatable switch may be manipulated by a user ofthe electric work machine to control operation (driving) of the motor.The motor drive circuit may be adapted/configured to drive the motor,using electric power supplied from the battery pack, in response to themanipulatable switch being manipulated. The drive mechanism may beadapted/configured to detachably mount or attach a work output member(e.g., a tool accessory) thereon or such that the work output member(e.g., a tool accessory) is integrally (permanently) affixed to thedrive mechanism. The drive mechanism may be adapted/configured to causethe work output member to act (e.g., rotate, linearly reciprocate orboth) on a work target by transmitting a rotational drive force of themotor and driving (e.g., moving) the work output member using thatrotational drive force.

With such an embodiment of a battery-connected system, datacommunication between the battery pack and the electric work machine maybe accurately executed (performed) owing to the first and secondlimiting circuits.

In the alternative, the connected equipment may comprise a charger,which has been adapted/configured to charge the battery.

With such an embodiment of a battery-connected system, datacommunication between the battery pack and the charger may be executedmore accurately (performed) owing to the first and second limitingcircuits.

In another aspect of the present disclosure, a battery pack isadapted/configured to be selectively placed in a connected state, inwhich the battery pack has been electrically connected to a connectedequipment (in particular, an electrical equipment, such as an electricwork machine (e.g., a power tool), a charger, etc.), and in a state, inwhich the connected state has been released (terminated).

The battery pack may comprise at least a battery, a pack positiveelectrode terminal, a pack negative electrode terminal, a packcommunication terminal, a data output circuit, a data input circuit, anda noise current limiting circuit or a reverse current protection circuit(hereinafter, simply “limiting circuit”).

The battery comprises a positive electrode and a negative electrode. Thepack positive electrode terminal is electrically connected to thepositive electrode of the battery and is adapted/configured to beelectrically connected to the connected equipment in response to thebattery pack entering the connected state (e.g., when the battery packis mounted on the connected equipment). The pack negative electrode iselectrically connected to the negative electrode of the battery and isadapted/configured to be electrically connected to the connectedequipment in response to the battery pack entering the connected state.The pack communication terminal may be adapted/configured to beelectrically connected to the connected equipment in response to thebattery pack entering the connected state. The data output circuitcomprises an output terminal connected to the pack communicationterminal and is adapted/configured to output first transmit-data fromthe output terminal. The data input circuit may comprise at least aninput terminal, which is electrically connected to the packcommunication terminal, and a ground terminal, which is electricallyconnected to the pack negative electrode terminal. The data inputcircuit is adapted/configured such that second transmit-data (one ormore signals containing data and/or instructions output by the connectedequipment), which has been input (transmitted) from the connectedequipment to the pack communication terminal, is input to (at) the inputterminal. The limiting circuit is adapted/configured to at least limit aflow of electric current (e.g., a noise current) in the direction fromthe pack negative electrode terminal to the pack communication terminalvia the data input circuit. That is, the limiting circuit is preferablydesigned to at least limit the flow of electric current (e.g., noise) inthe direction that is opposite (reverse) of the direction that thesecond-transmit data moves (flows) from the first communication terminalto the first input terminal. The limiting circuit is preferably designedto not limit the flow of electric current (e.g., signals) in thedirection that the second-transmit data moves (flows) from the firstcommunication terminal to the first input terminal.

With such an embodiment of a battery pack, because the limiting circuitis provided, the flow of electric current from the data input circuit tothe pack communication terminal and, in turn, the input of that electriccurrent to the connected equipment is limited, e.g., below a level thatdoes not detrimentally affect the signal integrity of thesecond-transmit data. Consequently, such a design makes it possible tomore accurately execute (perform data) communication between the batterypack and the connected equipment owing to the limiting circuit.

In yet another aspect of the present disclosure, an electric workmachine is adapted/configured to be selectively placed in a connectedstate, in which the electric work machine has been electricallyconnected to a battery pack comprising a battery (in particular, whenthe battery pack is mounted on the electric work machine (e.g., a powertool, outdoor power equipment, etc.)), and in a state, in which theconnected state has been released (terminated).

The electric work machine may comprise at least an equipment positiveelectrode terminal, an equipment negative electrode terminal, anequipment communication terminal, a data output circuit, a data inputcircuit, a noise current limiting circuit or a reverse currentprotection circuit (hereinafter, simply “limiting circuit”), amanipulatable switch (e.g., a trigger), a motor, a motor drive circuit(e.g., a PWM circuit), and a drive mechanism (e.g., a geartransmission).

The equipment positive electrode terminal is adapted/configured to beelectrically connected to the positive electrode of the battery inresponse to the electric work machine entering the connected state(e.g., when the battery pack is mounted on the electric work machine).The equipment negative electrode terminal is adapted/configured to beelectrically connected to the negative electrode of the battery inresponse to the electric work machine entering the connected state. Theequipment communication terminal is adapted/configured to beelectrically connected to the battery pack in response to the electricwork machine entering the connected state. The data output circuit maycomprise at least an output terminal, which is electrically connected tothe equipment communication terminal, and is adapted/configured tooutput equipment transmit-data (one or more signals containingdata/instructions generated and output by the electric work machine)from the output terminal. The data input circuit may comprise at leastan input terminal, which is electrically connected to the equipmentcommunication terminal, and a ground terminal, which is electricallyconnected to the equipment negative electrode terminal. The data inputcircuit may be adapted/configured such that battery transmit-data (oneor more signals containing data regarding the battery, such as, e.g.,current voltage, current temperature, etc.), which has been input(transmitted) from the battery pack to the equipment communicationterminal, is input to (at) the input terminal. The limiting circuit isadapted/configured to at least limit a flow of electric current in thedirection from from the equipment negative electrode terminal to theequipment communication terminal via the data input circuit. That is,the limiting circuit is preferably designed to at least limit the flowof electric current (e.g., noise) in the direction that is opposite(reverse) of the direction that the battery-transmit data moves (flows)from the equipment communication terminal to the input terminal. Thelimiting circuit is preferably designed to not limit the flow ofelectric current (e.g., signals) in the direction that thebattery-transmit data moves (flows) from the equipment communicationterminal to the input terminal.

The manipulatable switch is manipulated by a user of the electric workmachine to control operation/drive of the motor. The motor drive circuitis adapted/configured to drive the motor, using electric power suppliedfrom the battery pack through the equipment positive electrode terminaland the equipment negative electrode terminal, in response to themanipulatable switch being manipulated. The drive mechanism isadapted/configured to detachably mount or attach a work output member(e.g., a tool accessory) thereon or such that the work output member(e.g., a tool accessory) is integrally (permanently) affixed to thedrive mechanism. The drive mechanism is adapted/configured to cause thework output member to act on a work target by transmitting a rotationaldrive force of the motor and driving (e.g., moving) the work outputmember using that rotational drive force.

With such an embodiment an electric work machine, because the limitingcircuit is provided, the flow of electric current in the direction fromthe data input circuit to the equipment communication terminal and, inturn, the input of that electric current to the battery pack is limitede.g., below a level that does not detrimentally affect the signalintegrity of the battery-transmit data. Consequently, data communicationbetween the battery pack and the electric work machine can be executed(performed) more accurately owing to the limiting circuit.

In yet another aspect of the present disclosure, a chargeradapted/configured to be selectively placed in a connected state, inwhich the charger has been electrically connected to a battery packcomprising a battery (in particular, when the battery pack is mounted onthe charger to initiate a charging operation), and in a state, in whichthe connected state has been released (terminated).

The charger may comprise at least a charger positive electrode terminal,a charger negative electrode terminal, a charger communication terminal,a data output circuit, a data input circuit, a noise current limitingcircuit or a reverse current protection circuit (hereinafter, simply“limiting circuit”), and a charging circuit.

The charger positive electrode terminal is adapted/configured to beelectrically connected to the positive electrode of the battery inresponse to the charger entering the connected state. The chargernegative electrode terminal is adapted/configured to be electricallyconnected to the negative electrode of the battery in response to thecharger entering the connected state. The charger communication terminalis adapted/configured to be electrically connected to the battery packin response to the charger entering the connected state. The data outputcircuit may comprise at least an output terminal, which is electricallyconnected to the charger communication terminal, and isadapted/configured to output charger transmit-data (one or more signalscontaining data/instructions generated and output by the charger) fromthe output terminal. The data input circuit may comprise at least aninput terminal, which is electrically connected to the chargercommunication terminal, and a ground terminal, which is electricallyconnected to the charger negative electrode terminal. The data inputcircuit may be adapted/configured such that battery transmit-data (oneor more signals containing data regarding the battery, such as, e.g.,current voltage, current temperature, etc.), which has been input(transmitted) from the battery pack to the charger communicationterminal, is input to the input terminal. The limiting circuit isadapted/configured to at least limit a flow of electric current in adirection from the charger negative electrode terminal to the chargercommunication terminal via the data input circuit. That is, the limitingcircuit is preferably designed to at least limit the flow of electriccurrent (e.g., noise) in the direction that is opposite (reverse) of thedirection that the battery-transmit data moves (flows) from the chargercommunication terminal to the input terminal. The limiting circuit ispreferably designed to not limit the flow of electric current (e.g.,signals) in the direction that the battery-transmit data moves (flows)from the charger communication terminal to the input terminal.

The charging circuit is adapted/configured such that electric power forcharging the battery is output to the battery pack through the chargerpositive electrode terminal and the charger negative electrode terminal.

With such an embodiment of a charger, because the limiting circuit isprovided, the flow of electric current in the direction from the datainput circuit to the charger communication terminal and, in turn, theinput of that electric current to the battery pack is limited e.g.,below a level that does not detrimentally affect the signal integrity ofthe battery-transmit data. Consequently, data communication between thebattery pack and the charger can be executed (performed) more accuratelyowing to the limiting circuit.

Further objects, aspects, embodiments and advantages of the presentteachings will become apparent to a person skilled in the art uponreading the following detailed description in conjunction with theappended claims and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an explanatory diagram that shows the configuration of anelectric work machine system according to a first embodiment of thepresent disclosure.

FIG. 2 is an explanatory diagram that shows the configuration of acharging system according to the first embodiment.

FIG. 3 is an explanatory diagram that shows the configuration of anelectric work machine system according to a second embodiment of thepresent disclosure.

FIG. 4 is an explanatory diagram that shows the configuration of anelectric work machine system according to a third embodiment of thepresent disclosure.

FIG. 5 is an explanatory diagram that shows the configuration of anelectric work machine system according to a fourth embodiment of thepresent disclosure.

DETAILED DESCRIPTION OF THE INVENTION

Exemplary, non-limiting embodiments of the present disclosure areexplained below, with reference to the drawings.

1. First Embodiment

(1-1) Overview of an Exemplary Electric Work Machine System

The electric work machine system 1 shown in FIG. 1 comprises: a batterypack 10, which comprises (contains) a battery 14; and an electric workmachine 30. The electric work machine 30 is adapted/configured such thatthe battery pack 10 is mountable thereon and demountable (detachable,removable) therefrom. Specifically, the electric work machine 30comprises a mounting part 39, and the battery pack 10 is mountable onand demountable from the mounting part 39.

As shown in FIG. 1 , the battery pack 10 comprises a positive electrodeterminal 11, a negative electrode terminal 12, and a communicationterminal 13. The electric work machine 30 comprises a positive electrodeterminal 31, a negative electrode terminal 32, and a communicationterminal 33.

When the battery pack 10 is mounted on the electric work machine 30, theelectric work machine system 1 enters an equipment-connected state, inwhich the electric work machine 30 and the battery pack 10 areelectrically connected. In the equipment-connected state, as shown inFIG. 1 , the positive electrode terminal 11 of the battery pack 10 andthe positive electrode terminal 31 of the electric work machine 30 areelectrically connected, the negative electrode terminal 12 of thebattery pack 10 and the negative electrode terminal 32 of the electricwork machine 30 are electrically connected, and the communicationterminal 13 of the battery pack 10 and the communication terminal 33 ofthe electric work machine 30 are electrically connected.

When the electric work machine system 1 enters the equipment-connectedstate, it becomes possible for the electric work machine 30 to operateby receiving electric power (current) from the battery 14. When thebattery pack 10, which had been mounted on the electric work machine 30,is demounted (removed) from the electric work machine 30, theequipment-connected state is released (terminated). In addition, whenthe electric work machine system 1 enters the equipment-connected state,data communication (e.g., half duplex serial communication) between theelectric work machine 30 and the battery pack 10 becomes possible.

(1-2) Configuration of an Exemplary Battery Pack

As shown in FIG. 1 , in addition to the positive electrode terminal 11,the negative electrode terminal 12, the communication terminal 13, andthe battery 14 described above, the battery pack 10 further comprises abattery control circuit (e.g., a microprocessor unit comprising at leastone processor, memory having operating programs and data stored thereinand at least one I/O interface) 20, a power supply circuit 21, a currentdetection circuit 22, a data input circuit 23, and a data output circuit24.

The battery 14 is a rechargeable battery, which is capable of beingcharged and discharged. The battery 14 may contain one or more batterycells of any kind of rechargeable battery, for example, one or morelithium ion battery cells. The rated voltage value of the battery 14 maybe any value without limitation, for example, 36 V. Generally speaking,batteries 14 according to the present teachings may beadapted/configured to output any rated voltage within a range of about10-100 V, such as, e.g., 14-40 V.

The positive electrode terminal 11 is electrically connected to thepositive electrode of the battery 14. The negative electrode terminal 12is electrically connected to the negative electrode of the battery 14.In greater detail, the negative electrode terminal 12 is electricallyconnected to the negative electrode of the battery 14 via the currentdetection circuit 22 and a ground line 15.

The current detection circuit 22 outputs, to the battery control circuit20, a current detection signal corresponding to the value of theelectric current flowing through a negative electrode path, whichextends from the negative electrode terminal 12 to the negativeelectrode of the battery 14 via the ground line 15. The currentdetection circuit 22 may be any kind of circuit capable of detecting thevalue of the current momentarily flowing, e.g., from the battery 14 tothe electric work machine 30 and/or from a charger to the battery 14.For example, the current detection circuit 22 may comprise a shuntresistor (not shown) that is inserted in (in series with) the negativeelectrode path. In the alternative, the current detection circuit 22 maybe provided at a location that differs from the negative electrode path.In such an alternative embodiment, the negative electrode terminal 12may be directly connected to the ground line 15.

The communication terminal 13 is electrically connected to the datainput circuit 23 and to the data output circuit 24. In greater detail, afirst end of a signal path 26 is connected to the communication terminal13, and a second end of the signal path 26 is connected to the datainput circuit 23. Thus, the communication terminal 13 is electricallyconnected to the data input circuit 23 via the signal path 26.

The data output circuit 24 is electrically connected to a connectionpoint 26 a in the signal path 26 and is electrically connected to thecommunication terminal 13 via the connection point 26 a.

A resistor R10 is provided in (in series with) the signal path 26between the connection point 26 a and the communication terminal 13. Adiode D11 is provided in (in series with) the signal path 26 between theconnection point 26 a and the data input circuit 23. Specifically, theanode of the diode D11 is electrically connected to the connection point26 a, and the cathode of the diode D11 is electrically connected to thedata input circuit 23.

It is noted that the connection point 26 a may be provided in the signalpath 26 anywhere between the anode of the diode D11 and thecommunication terminal 13. For example, the connection point 26 a may beprovided between the resistor R10 and the communication terminal 13. Inaddition, for example, the connection point 26 a may be provided in thesignal path 26 at the end part to which the communication terminal 13 isconnected (in other words, at the location of the communication terminal13 to which the signal path 26 is connected).

The battery control circuit 20 controls the charging and the dischargingof the battery 14 based on various types of information that are inputinto the battery control circuit 20, such as the current detectionsignal input from the current detection circuit 22.

The battery pack 10 of the present embodiment comprises a universalasynchronous receiver transmitter (UART) circuit, which is embodied inthe data input circuit 23, the data output circuit 24, and thecommunication terminal 13. The battery control circuit 20 preferablyperforms half duplex serial communication with the electric work machine30, which is connected to the battery pack 10 via the UART circuit.

The battery control circuit 20 comprises a Tx terminal 20 a and an Rxterminal 20 b. The battery control circuit 20 generates batterytransmit-data (one or more signals) and outputs such from the Txterminal 20 a. The battery transmit-data, which has been output from theTx terminal 20 a, is transmitted to the electric work machine 30 via thedata output circuit 24 and the communication terminal 13. Equipmenttransmit-data (one or more signals) is transmitted from the electricwork machine 30. In the battery pack 10, this equipment transmit-data isinput (received) at the communication terminal 13 and then input to theRx terminal 20 b via the data input circuit 23. In the presentembodiment, the battery transmit-data and the equipment transmit-dataare in each case implemented, for example, as a binary signal having anH level (high or “1”) and an L level (low or “0”).

The battery control circuit 20 executes (performs) data communication(serial communication) with the electric work machine 30 via the datainput circuit 23 and the data output circuit 24 and controls thedischarging of the battery 14 (i.e. the supply of power (current) to theconnected equipment) in accordance with the equipment transmit-datareceived from the electric work machine 30.

The power supply circuit 21 generates a direct current control voltageVDD_B by stepping down the voltage of the battery 14. The controlvoltage VDD_B generated by the power supply circuit 21 is supplied toeach component within the battery pack 10, including to the batterycontrol circuit 20, the data input circuit 23, and the data outputcircuit 24.

The data input circuit 23 and the data output circuit 24 will now beexplained in further detail. As shown in FIG. 1 , the data input circuit23 comprises a switching device T11, resistors R11, R12, R13, an inputterminal 23 a, and a ground terminal 23 b. In the present embodiment,the switching device T11 is, for example, an n-channel MOSFET.

The second end of the signal path 26 is electrically connected to theinput terminal 23 a. That is, the cathode of the diode D11, which isprovided in the signal path 26, is electrically connected to the inputterminal 23 a. Thereby, the equipment transmit-data, which has beeninput (transmitted) from the electric work machine 30 to thecommunication terminal 13, is input to the input terminal 23 a via thesignal path 26 (i.e., via the resistor R10 and the diode D11). Theground terminal 23 b is electrically connected to the ground line 15.

In the data input circuit 23, a first end of the resistor R11 iselectrically connected to the input terminal 23 a, and a second end ofthe resistor R11 is electrically connected to the gate (switch inputterminal) of the switching device T11. The source (switch groundterminal) of the switching device T11 is electrically connected to theground terminal 23 b, and the drain of the switching device T11 iselectrically connected both to a first end of the resistor R13 and tothe Rx terminal 20 b. The control voltage VDD_B is input to a second endof the resistor R13. A first end of the resistor R12 is electricallyconnected to a connection point 23 c, and a second end of the resistorR12 is electrically connected to a connection point 23 d. The connectionpoint 23 c is provided along (in series with) a path extending from thesecond end of the resistor R11 to the gate of the switching device T11.The connection point 23 d is provided along (in series with) a pathextending from the source of the switching device T11 to the groundterminal 23 b.

In the above-described data input circuit 23, if the communicationterminal 13 becomes H level (high) in response to the equipmenttransmit-data transmitted from the electric work machine 30, then theswitching device T11 turns ON and an L-level (low) signal is output tothe Rx terminal 20 b. On the other hand, if the communication terminal13 becomes L level (low) in response to the equipment transmit-data, theswitching device T11 turns OFF and an H-level (high) signal is output tothe Rx terminal 20 b.

As shown in FIG. 1 , the data output circuit 24 comprises a switchingdevice T12, resistors R14, R15, a diode D12, and an output terminal 24a. In the present embodiment, the switching device T12 is, for example,a p-channel MOSFET. The output terminal 24 a is electrically connectedto the connection point 26 a in the signal path 26.

A first end of the resistor R14 is electrically connected to the Txterminal 20 a, and a second end of the resistor R14 is electricallyconnected to the gate of the switching device T12. A first end of theresistor R15 is electrically connected to the gate of the switchingdevice T12, and a second end of the resistor R15 is electricallyconnected to the source of the switching device T12. Control voltageVDD_B is input to the source of the switching device T12. The anode ofthe diode D12 is electrically connected to the drain of the switchingdevice T12, and the cathode of the diode D12 is electrically connectedto the output terminal 24 a.

(1-3) Configuration of an Exemplary Electric Work Machine

As shown in FIG. 1 , in addition to the positive electrode terminal 31,the negative electrode terminal 32, and the communication terminal 33described above, the electric work machine 30 further comprises a motor34, a manipulatable switch (e.g., trigger) 36, a drive mechanism (e.g.,a speed-reducing gear transmission and/or a rotational-to-linear motionconverting mechanism) 37, a drive control circuit (e.g., amicroprocessor unit comprising at least one processor, memory havingoperating programs and data stored therein and at least one I/Ointerface) 40, a power supply circuit 41, a drive switch (e.g., a FET)42, a data input circuit 43, a data output circuit 44, and a motor drivecircuit (e.g., a pulse-width-modulation (PWM) drive circuit) 45.

The motor drive circuit 45 is connected both to the positive electrodeterminal 31 (via the drive switch 42) and to the negative electrodeterminal 32 and is adapted/configured to receive (input) electric power(current) from the battery 14 of the battery pack 10, which is mountedon the mounting part 39. In accordance with a drive instruction that hasbeen input from the drive control circuit 40, the motor drive circuit 45converts the electric power (current), which was supplied by the battery14, into drive power (current, e.g., according to a pulse-widthmodulated duty cycle) for driving (powering) the motor 34 and suppliessuch drive power (current) to the motor 34.

The motor 34 rotates owing to the drive power supplied from the motordrive circuit 45. The motor 34 may be any kind of motor, such as, forexample, a brushless motor or a brushed DC motor.

A work output member (e.g., a tool accessory) 38 is provided on anoutput end/portion of the drive mechanism 37. The work output member 38may be affixed to (integral with) the drive mechanism 37 (e.g., to/witha spindle thereof) or may be removable or detachable from the drivemechanism 37. The rotational drive force generated by the rotation ofthe motor 34 is transmitted to the drive mechanism 37. Using therotational drive force transmitted from the motor 34, the drivemechanism 37 drives the work output member 38 attached to the drivemechanism 37, e.g., rotationally, linearly and/or both rotationally andlinearly.

The work output member 38 acts on a work target, which is external to(separate from) the electric work machine 30; in other words, the workoutput member 38 is adapted/configured to achieve or realize thefunction (intended purpose) of the electric work machine 30 by impartingenergy to the work target. The work output member 38 may be, forexample, a rotary blade adapted/configured to rotate in order to mowgrass, brush cut small diameter trees, or the like. In the alternative,for example, the work output member 38 may be a drill bitadapted/configured to rotate in order to drill a hole in a workpiece. Inthe alternative, for example, the work output member 38 may be a fanthat is rotated in order to blow or suck air (which is the work targetin this embodiment).

The drive switch 42 for making conductive and interrupting theconducting path is provided in (in series with) the conducting pathbetween the positive electrode terminal 31 and the motor drive circuit45. The drive switch 42 is turned ON and OFF by the drive controlcircuit 40.

The manipulatable switch 36 is designed to be manipulated or moved(e.g., squeezed, pulled) by a user of the electric work machine 30. Inresponse to the manipulatable switch 36 being manipulated, the drivecontrol circuit 40 causes the motor 34 to be rotationally driven byturning the drive switch 42 ON to make the above-described conductingpath conductive and then outputting a drive instruction to the motordrive circuit 45.

The communication terminal 33 is electrically connected to the datainput circuit 43 and to the data output circuit 44. In greater detail, afirst end of a signal path 46 is electrically connected to thecommunication terminal 33, and a second end of the signal path 46 iselectrically connected to the data input circuit 43. The communicationterminal 33 is electrically connected to the data input circuit 43 viathe signal path 46.

The data output circuit 44 is electrically connected to a connectionpoint 46 a and is electrically connected to the communication terminal33 via the connection point 46 a. A resistor R30 is provided in (inseries with) the signal path 46 between the connection point 46 a andthe communication terminal 33. A diode D31 is provided in (in serieswith) the signal path 46 between the connection point 46 a and the datainput circuit 43. Specifically, the anode of the diode D31 iselectrically connected to the connection point 46 a, and the cathode ofthe diode D31 is electrically connected to the data input circuit 43.

It is noted that the connection point 46 a may be provided in the signalpath 46 anywhere between the anode of the diode D31 and thecommunication terminal 33. For example, the connection point 46 a may beprovided between the resistor R30 and the communication terminal 33. Inthe alternative, for example, the connection point 46 a may be providedin the signal path 46 at the end part to which the communicationterminal 33 is connected (in other words, at the location of thecommunication terminal 33 to which the signal path 46 is connected).

The electric work machine 30 of the present embodiment comprises theUART circuit, which is embodied by the data input circuit 43, the dataoutput circuit 44, and the communication terminal 33. The drive controlcircuit 40 executes (performs) half duplex serial communication with thebattery pack 10, which is connected to the electric work machine 30, viathe UART circuit.

The drive control circuit 40 comprises a Tx terminal 40 a and an Rxterminal 40 b. The drive control circuit 40 generates theabove-described equipment transmit-data and outputs such from the Txterminal 40 a. The equipment transmit-data, which has been output fromthe Tx terminal 40 a, is transmitted to the battery pack 10 via the dataoutput circuit 44 and the communication terminal 33. The batterytransmit-data transmitted from the battery pack 10 is, in the electricwork machine 30, received (input) at the communication terminal 33 andinput to the Rx terminal 40 b via the data input circuit 43.

The power supply circuit 41 generates a direct current control voltageVDD_E by stepping down the voltage of the battery 14, which is inputfrom the battery pack 10 mounted on the electric work machine 30. Thecontrol voltage VDD_E generated by the power supply circuit 41 issupplied to each component within the electric work machine 30,including the drive control circuit 40, the data input circuit 43, andthe data output circuit 44. It is noted that the value of controlvoltage VDD_E may be the same as or different from the value of controlvoltage VDD_B generated by the battery pack 10.

The data input circuit 43 and the data output circuit 44 will now beexplained in further detail. As shown in FIG. 1 , the data input circuit43 comprises a switching device T31, resistors R31, R32, R33, an inputterminal 43 a, and a ground terminal 43 b. In the present embodiment,the switching device T31 is, for example, an n-channel MOSFET.

The second end of the signal path 46 is electrically connected to theinput terminal 43 a. That is, the cathode of the diode D31, which isprovided in the signal path 46, is electrically connected to the inputterminal 43 a. Thereby, the battery transmit-data, which has been input(transmitted) from the battery pack 10 to the communication terminal 33,is input to the input terminal 43 a via the signal path 46 (i.e., viathe resistor R30 and the diode D31). The ground terminal 43 b iselectrically connected to a ground line 35. The negative electrodeterminal 32 and the motor drive circuit 45 are electrically connected tothe ground line 35.

In the data input circuit 43, a first end of the resistor R31 iselectrically connected to the input terminal 43 a, and a second end ofthe resistor R31 is electrically connected to the gate (switch inputterminal) of the switching device T31. The source (switch groundterminal) of the switching device T31 is electrically connected to theground terminal 43 b, and the drain of the switching device T31 iselectrically connected both to a first end of the resistor R33 and tothe Rx terminal 40 b. The control voltage VDD_E is input to a second endof the resistor R33.

A first end of the resistor R32 is electrically connected to aconnection point 43 c, and a second end of the resistor R32 iselectrically connected to a connection point 43 d. The connection point43 c is provided along (in series with) a path extending from the secondend of the resistor R31 to the gate of the switching device T31. Theconnection point 43 d is provided along (in series with) a pathextending from the source of the switching device T31 to the groundterminal 43 b.

In the above-described data input circuit 43, if the communicationterminal 33 becomes H level (high or “1”) in response to the batterytransmit-data from the battery pack 10, then the switching device T31turns ON and an L-level signal (low or “0”) is output to the Rx terminal40 b. On the other hand, if the communication terminal 33 becomes Llevel in response to the battery transmit-data, the switching device T31turns OFF and an H-level signal is output to the Rx terminal 40 b.

As shown in FIG. 1 , the data output circuit 44 comprises a switchingdevice T32, resistors R34, R35, a diode D32, and an output terminal 44a. In the present embodiment, the switching device T32 is, for example,a p-channel MOSFET. The output terminal 44 a is connected to theconnection point 46 a.

A first end of the resistor R34 is electrically connected to the Txterminal 40 a of the drive control circuit 40, and a second end of theresistor R34 is electrically connected to the gate of the switchingdevice T32. A first end of the resistor R35 is electrically connected tothe gate of the switching device T32, and a second end of the resistorR35 is electrically connected to the source of the switching device T32.Control voltage VDD_E is input to the source of the switching deviceT32. The anode of the diode D32 is electrically connected to the drainof the switching device T32, and the cathode of the diode D32 iselectrically connected to the output terminal 44 a.

(1-4) Overview of an Exemplary Charging System

The charging system 2 shown in FIG. 2 comprises the battery pack 10 anda charger 50. The battery pack 10 shown in FIG. 2 is the same as thebattery pack 10 shown in FIG. 1 . The charger 50 is adapted/configuredsuch that the battery pack 50 is mountable thereon and demountabletherefrom. Specifically, the charger 50 comprises a mounting part 59,and the battery pack 10 is mountable on and demountable from themounting part 59.

As shown in FIG. 2 , the charger 50 comprises a positive electrodeterminal 51, a negative electrode terminal 52, and a communicationterminal 53. When the battery pack 10 is mounted on the charger 50, thecharging system 2 enters a charger-connected state, in which the charger50 and the battery pack 10 are electrically connected. In thecharger-connected state, as shown in FIG. 2 , the positive electrodeterminal 11 of the battery pack 10 and the positive electrode terminal51 of the charger 50 are electrically connected, the negative electrodeterminal 12 of the battery pack 10 and the negative electrode terminal52 of the charger 50 are electrically connected, and the communicationterminal 13 of the battery pack 10 and the communication terminal 53 ofthe charger 50 are electrically connected.

When the charging system 2 enters the charger-connected state, itbecomes possible for the charger 50 to supply charging power (current)to the battery pack 10 and thereby charge the battery 14. When thebattery pack 10, which has been mounted on the charger 50, is demountedfrom the charger 50, the charger-connected state is released(terminated). In addition, when the charging system 2 enters thecharger-connected state, data communication (e.g., half duplex serialcommunication) between the charger 50 and the battery pack 10 becomespossible.

(1-5) Configuration of an Exemplary Charger

As shown in FIG. 2 , in addition to the positive electrode terminal 51,the negative electrode terminal 52, and the communication terminal 53described above, the charger 50 further comprises a power supply plug54, a charger control circuit (e.g., a microprocessor unit comprising atleast one processor, memory having operating programs and data storedtherein and at least one I/O interface) 60, a charger switch (e.g., aFET) 62, a data input circuit 63, a data output circuit 64, and acharger power supply circuit 65.

The power supply plug 54 is electrically connected to an AC powersupply, for example, a commercial power supply that supplies 110 or 220VAC, and is adapted/configured to receive AC electrical power from theAC power supply.

The charger power supply circuit 65 generates, from the AC electricalpower that is input via the power supply plug 54 (i.e. via a power cordthat electrically connects the plug 54 and the charger power supplycircuit 65), the charging power for charging the battery 14. The chargerpower supply circuit 65 is electrically connected to the positiveelectrode terminal 51 via the charger switch 62 and is electricallyconnected to the negative electrode terminal 52. The charging powergenerated by the charger power supply circuit 65 is supplied, via thepositive electrode terminal 51 and the negative electrode terminal 52,to the battery pack 10, which has been mounted on the charger 50.

The charger switch 62 is provided along (in series with) a chargingpath, extending between the charger power supply circuit 65 and thepositive electrode terminal 51, for outputting the charging power. Thecharger switch 62 is configured/adapted to make the charging pathconductive and to interrupt the charging path.

The charger control circuit 60 controls the charger power supply circuit65 and the charger switch 62. When the battery pack 10 is mounted on thecharger 50 and charging of the battery 14 is possible, the chargercontrol circuit 60 makes the above-described charging path conductive byturning the charger switch 62 ON and thereby supplies charging power tothe battery pack 10 by causing the charger power supply circuit 65 togenerate charging power.

It is noted that the charger power supply circuit 65 has a function(intended purpose) of generating a direct current control voltage VDD_Cfrom the AC power supply, which has been input via the power supply plug54. Control voltage VDD_C generated by the charger power supply circuit65 is supplied to every component within the charger 50, including thecharger control circuit 60, the data input circuit 63, and the dataoutput circuit 64. It is noted that the value of control voltage VDD_Cmay be the same as or different from the value of control voltage VDD_Bgenerated by the battery pack 10.

The communication terminal 53 is electrically connected to the datainput circuit 63 and the data output circuit 64. In greater detail, afirst end of a signal path 66 is electrically connected to thecommunication terminal 53, and a second end of the signal path 66 iselectrically connected to the data input circuit 63. The communicationterminal 53 is electrically connected to the data input circuit 63 viathe signal path 66.

The data output circuit 64 is electrically connected to a connectionpoint 66 a in the signal path 66 and is electrically connected to thecommunication terminal 53 via the connection point 66 a.

A resistor R50 is provided in (in series with) the signal path 66between the connection point 66 a and the communication terminal 53. Adiode D51 is provided in (in series with) the signal path 66 between theconnection point 66 a and the data input circuit 63. Specifically, theanode of the diode D51 is electrically connected to the connection point66 a, and the cathode of the diode D51 is electrically connected to thedata input circuit 63.

It is noted that the connection point 66 a may be provided in the signalpath 66 anywhere between the anode of the diode D51 and thecommunication terminal 53. For example, the connection point 66 a may beprovided between the resistor R50 and the communication terminal 53. Inaddition, for example, the connection point 66 a may be provided in thesignal path 66 at the end part to which the communication terminal 53 isconnected (in other words, at the location of the communication terminal53 to which the signal path 66 is connected).

The charger 50 of the present embodiment comprises the UART circuit,which is embodied by the data input circuit 63, the data output circuit64, and the communication terminal 53. The charger control circuit 60performs half duplex serial communication with the battery pack 10,which is connected to the charger 50, via the UART circuit.

The charger control circuit 60 comprises a Tx terminal 60 a and an Rxterminal 60 b. The charger control circuit 60 generates the chargertransmit-data (one or more signals, e.g., comprising charginginstructions) and outputs such from the Tx terminal 60 a. The chargertransmit-data output from the Tx terminal 60 a is transmitted to thebattery pack 10 via the data output circuit 64 and the communicationterminal 53. The battery transmit-data transmitted from the battery pack10 is, in the charger 50, input at the communication terminal 53 and theinput to the Rx terminal 60 b via the data input circuit 63.

The data input circuit 63 and the data output circuit 64 will now beexplained in further detail. As shown in FIG. 2 , the data input circuit63 comprises a switching device T51, resistors R51, R52, R53, an inputterminal 63 a, and a ground terminal 63 b. In the present embodiment,the switching device T51 is, for example, an n-channel MOSFET.

The second end of the signal path 66 is electrically connected to theinput terminal 63 a. That is, the cathode of the diode D51, which isprovided in the signal path 66, is electrically connected to the inputterminal 63 a. Thereby, the battery transmit-data, which has been inputfrom the battery pack 10 to the communication terminal 53, is input(transmitted) to the input terminal 63 a via the signal path 66 (i.e.,via the resistor R50 and the diode D51). The ground terminal 63 b iselectrically connected to a ground line 55. The negative electrodeterminal 52 and the charger power supply circuit 65 are electricallyconnected to the ground line 55.

In the data input circuit 63, a first end of the resistor R51 iselectrically connected to the input terminal 63 a, and a second end ofthe resistor R51 is electrically connected to the gate (switch inputterminal) of the switching device T51. The source (switch groundterminal) of the switching device T51 is electrically connected to theground terminal 63 b, and the drain of the switching device T51 iselectrically connected both to a first end of the resistor R53 and tothe Rx terminal 60 b. The control voltage VDD_C is input to a second endof the resistor R53. A first end of the resistor R52 is electricallyconnected to a connection point 63 c, and a second end of the resistorR52 is electrically connected to a connection point 63 d. The connectionpoint 63 c is provided along (in series with) a path extending from thesecond end of the resistor R51 to the gate of the switching device T51.The connection point 63 d is provided along (in series with) a pathextending from the source of the switching device T51 to the groundterminal 63 b.

In the above-described data input circuit 63, if the communicationterminal 53 becomes H level (high or “1”) in response to the batterytransmit-data from the battery pack 10, then the switching device T51turns ON and an L-level signal (low or “0”) is output to the Rx terminal60 b. On the other hand, if the communication terminal 53 becomes Llevel in response to the battery transmit-data, the switching device T51turns OFF and an H-level signal is output to the Rx terminal 60 b.

As shown in FIG. 2 , the data output circuit 64 comprises a switchingdevice T52, resistors R54, R55, a diode D52, and an output terminal 64a. In the present embodiment, the switching device T52 is, for example,a p-channel MOSFET. The output terminal 64 a is connected to theconnection point 66 a.

A first end of the resistor R54 is electrically connected to the Txterminal 60 a, and a second end of the resistor R54 is electricallyconnected to the gate of the switching device T52. A first end of theresistor R55 is electrically connected to the gate (switch inputterminal) of the switching device T52, and a second end of the resistorR55 is electrically connected to the source (switch ground terminal) ofthe switching device T52. Control voltage VDD_C is input to the sourceof the switching device T52. The anode of the diode D52 is electricallyconnected to the drain of the switching device T52, and the cathode ofthe diode D52 is electrically connected to the output terminal 64 a.

(1-6) Noise Current Limiting (Protection) Function and Effects Thereof

Next, a noise current limiting (protection) function, which the electricwork machine system 1 and the charging system 2 of the presentembodiment possess, and the effects thereof will be explained.

First, it is noted that the electric work machine system 1 shown in FIG.1 utilizes a single communication path (i.e. the connection terminals13, 33) to communicate signals from the battery pack 10 to the electricwork machine 30 and vice versa. Thus, a half-duplex communication systemis preferably used, because it enables communications in two directions,but only one direction at a time. In half-duplex systems, if signals,voltages, etc. are transmitted in both directions at the same time(e.g., a signal in one direction and noise in the other direction), acollision may occur, thereby possibly resulting in a lostmessage/signal.

More specifically, the electric work machine system 1 shown in FIG. 1includes a closed loop that, in clockwise order in FIG. 1 starting from,for example, the negative electrode terminal 12 of the battery pack 10,includes the current detection circuit 22, the connection point of theground line 15 with the data input circuit 23, the data input circuit 23(including the resistor R12), the signal path 26, the communicationterminal 13, the communication terminal 33 of the electric work machine30, the signal path 46, the data input circuit 43 (including theresistor R32), and the connection point of the ground line 35 with thedata input circuit 43, from which the closed loop returns to thenegative electrode terminal 12 of the battery pack 10 via the negativeelectrode terminal 32.

If an unintended noise current were to flow through the above-describedclosed loop, e.g., owing to noise generated during the drive of themotor 34 in the electric work machine 30 or various other factors, whilea signal is being transmitted in the opposite direction, then there is apossibility that the battery control circuit 20 or the drive controlcircuit 40 will be affected by that noise current and will becomeincapable to accurately receive data such that the signal is lost whilethe noise current is flowing. More specifically, if a noise currentflows, for example, in the direction from the communication terminal 13of the battery pack 10 in the above mentioned closed loop toward thecommunication terminal 33 of the electric work machine 30 (i.e., in theclockwise direction in FIG. 1 ) while battery transmit-data is beingtransmitted by the battery pack 10 in the opposite direction, then thereis a possibility that the drive control circuit 40 of the electric workmachine 30 will not be able to accurately receive the batterytransmit-data while this noise current is flowing owing to a collisionbetween the battery transmit-data and the noise current. Conversely, ifa noise current flows in the direction from the communication terminal33 of the electric work machine 30 in the above mentioned closed looptoward the communication terminal 13 of the battery pack 10 (i.e., inthe counterclockwise direction in FIG. 1 ) while equipment transmit-datais being transmitted by the electric work machine 30 or charger 50 inthe opposite direction, then there is a possibility that the batterycontrol circuit 20 of the battery pack 10 will not be able to accuratelyreceive the equipment transmit-data while this noise current is flowingowing to a collision between the equipment transmit-data and the noisecurrent. In other words, the noise (voltage) moving in one direction mayaffect (offset) the signal (voltage) moving in the opposite direction toan extent that the signal integrity is lost and the signal can not beproperly received/discerned at the intended receiver.

Accordingly, in the electric work machine system 1 according to thepresent embodiment, in order to sufficiently limit or even blockundesirable noise currents flowing in the closed loop, the diode D11 isprovided in the signal path 26 of the battery pack 10, and the diode D31is provided in the signal path 46 of the electric work machine 30. Noisecurrents that flow clockwise through the closed loop are limited (e.g.,at least partially blocked, truncated, reduced, or the like) by thediode D11 of the battery pack 10, thereby providing reverse currentprotection. Noise currents that flow counterclockwise through the closedloop are limited (e.g., at least partially blocked, truncated, reduced,diminished or the like) by the diode D31 of the electric work machine 30or the diode D51 of the charger 50. That is, in principle, diodes areasymmetrically conductive such that the diode has low resistance in onedirection (cathode to anode) and a high resistance in the otherdirection (anode to cathode). The noise-limiting diodes D11, D31, D51are arranged so that signals can pass in the direction of lowresistance, whereas noise currents flowing in the opposite direction areat least substantially reduced so that any noise that passes through thediode D11, D31, D51 (i.e. in the direction from the anode to thecathode) does not detrimentally influence or affect the signal integrityof the desired signals moving in the opposite direction (i.e. in thedirection from the cathode to the anode).

Therefore, in the battery pack 10, the diode D11 is provided in thesignal path 26 on the data input circuit 23 side of the connection point26 a. Consequently, any decrease in the quality (signal integrity) ofthe battery transmit-data, which is transmitted from the data outputcircuit 24 to the electric work machine 30 via the communicationterminal 13, caused by a noise current flowing in the opposite directionis limited by the diode D11, whereby the effect of any noise currents onthe battery transmit-data is suitably limited (restricted, diminished).

Similarly, in the electric work machine 30, the diode D31 is provided inthe signal path 46 on the data input circuit 43 side of the connectionpoint 46 a. Consequently, any decrease in the quality (signal integrity)of the equipment transmit-data, which is transmitted from the dataoutput circuit 44 to the battery pack 10 via the communication terminal33, caused by a noise current flowing in the opposite direction islimited by the diode D31, whereby the effect of any noise currents onthe equipment transmit-data is suitably limited (restricted,diminished).

The charging system 2 shown in FIG. 2 likewise has a closed loop, thesame as in the electric work machine system 1. In the charging system 2,too, there is a possibility that, owing to various factors, noisecurrents will be generated and flow such that they circulate through theclosed loop. However, in the charging system 2 according to the presentembodiment, the diode D11 is provided in the signal path 26 of thebattery pack 10, and the diode D51 is provided in the signal path 66 ofthe charger 50. Consequently, in the charging system 2, too, noisecurrents, which flow such that they circulate through the closed loop,are suitably limited (restricted, diminished) by the diodes D11 and D51,thereby providing reverse current protection.

More specifically, in the charger 50, the diode D51 is provided in thesignal path 66 on the data input circuit 63 side of the connection point66 a. Consequently, any decrease in the quality (signal integrity) ofthe charger transmit-data, which is transmitted from the data outputcircuit 64 to the battery pack 10 via the communication terminal 53,caused by a noise current flowing in the opposite direction is limitedby the diode D51, whereby the effect of the noise currents on thecharger transmit-data is suitably limited (restricted, diminished).

It is noted that the electric work machine 30 and the charger 50correspond to exemplary examples of connected equipment according to thepresent disclosure.

In the battery pack 10, the positive electrode terminal 11 correspondsto one example of a first positive electrode terminal and a packpositive electrode terminal in the present disclosure. The negativeelectrode terminal 12 corresponds to one example of a first negativeelectrode terminal and a pack negative electrode terminal in the presentdisclosure. The communication terminal 13 corresponds to one example ofa first communication terminal and a pack communication terminal in thepresent disclosure. The data input circuit 23 corresponds to one exampleof a first data input circuit in the present disclosure. The inputterminal 23 a corresponds to one example of a first input terminal inthe present disclosure. The ground terminal 23 b corresponds to oneexample of a first ground terminal in the present disclosure. Theswitching device T11 corresponds to one example of a first switchingdevice in the present disclosure. The gate of the switching device T11corresponds to one example of a first switch input terminal in thepresent disclosure. The source of the switching device T11 correspondsto one example of a first switch ground terminal in the presentdisclosure. The resistor R12 corresponds to one example of a firstresistor in the present disclosure. The conducting path connecting theconnection point 23 c and the connection point 23 d and in which theresistor R12 is provided corresponds to one example of a first bias pathin the present disclosure. The data output circuit 24 corresponds to oneexample of a first data output circuit in the present disclosure. Theoutput terminal 24 a corresponds to one example of a first outputterminal in the present disclosure. The signal path 26 corresponds toone example of a first signal path in the present disclosure. Theconnection point 26 a in the signal path 26 corresponds to one exampleof a first connection point in the present disclosure. The diode D11corresponds to one example of a first limiting circuit, a first reversecurrent protection circuit, and a first diode in the present disclosure.

In the electric work machine 30, the positive electrode terminal 31corresponds to one example of a second positive electrode terminal andan equipment positive electrode terminal in the present disclosure. Thenegative electrode terminal 32 corresponds to one example of a secondnegative electrode terminal and an equipment negative electrode terminalin the present disclosure. The communication terminal 33 corresponds toone example of a second communication terminal and an equipmentcommunication terminal in the present disclosure. The data input circuit43 corresponds to one example of a second data input circuit in thepresent disclosure. The input terminal 43 a corresponds to one exampleof a second input terminal in the present disclosure. The groundterminal 43 b corresponds to one example of a second ground terminal inthe present disclosure. The switching device T31 corresponds to oneexample of a second switching device in the present disclosure. The gateof the switching device T31 corresponds to one example of a secondswitch input terminal in the present disclosure. The source of theswitching device T31 corresponds to one example of a second switchground terminal in the present disclosure. The resistor R32 correspondsto one example of a second resistor in the present disclosure. Theconducting path connecting the connection point 43 c and the connectionpoint 43 d and in which the resistor R32 is provided corresponds to oneexample of a second bias path in the present disclosure. The data outputcircuit 44 corresponds to one example of a second data output circuit inthe present disclosure. The output terminal 44 a corresponds to oneexample of a second output terminal in the present disclosure. Thesignal path 46 corresponds to one example of a second signal path in thepresent disclosure. The connection point 46 a in the signal path 46corresponds to one example of a second connection point in the presentdisclosure. The diode D31 corresponds to one example of a secondlimiting circuit, a second reverse current protection circuit, and asecond diode in the present disclosure.

In the charger 50, the positive electrode terminal 51 corresponds to oneexample of the second positive electrode terminal and a charger positiveelectrode terminal in the present disclosure. The negative electrodeterminal 52 corresponds to one example of the second negative electrodeterminal and a charger negative electrode terminal in the presentdisclosure. The communication terminal 53 corresponds to one example ofthe second communication terminal and a charger communication terminalin the present disclosure. The data input circuit 63 corresponds to oneexample of the second data input circuit in the present disclosure. Theinput terminal 63 a corresponds to one example of the second inputterminal in the present disclosure. The ground terminal 63 b correspondsto one example of the second ground terminal in the present disclosure.The switching device T51 corresponds to one example of the secondswitching device in the present disclosure. The gate of the switchingdevice T51 corresponds to one example of the second switch inputterminal in the present disclosure. The source of the switching deviceT51 corresponds to one example of the second switch ground terminal inthe present disclosure. The resistor R52 corresponds to one example ofthe second resistor in the present disclosure. The conducting pathconnecting the connection point 63 c and the connection point 63 d andin which the resistor R52 is provided corresponds to one example of thesecond bias path in the present disclosure. The data output circuit 64corresponds to one example of the second data output circuit in thepresent disclosure. The output terminal 64 a corresponds to one exampleof the second output terminal in the present disclosure. The signal path66 corresponds to one example of the second signal path in the presentdisclosure. The connection point 66 a in the signal path 66 correspondsto one example of the second connection point in the present disclosure.The diode D51 corresponds to another example of the second limitingcircuit, the second reverse current protection circuit, and the seconddiode in the present disclosure.

2. Second Embodiment

An electric work machine system 3 according to a second embodiment willnow be explained, with reference to FIG. 3 . Because the basicconfiguration of the electric work machine system 3 according to thesecond embodiment is the same as that of the electric work machinesystem 1 according to the first embodiment, only those points ofdifference from the electric work machine system 1 will be explainedbelow. It is noted that symbols in the second embodiment that are thesame as those in the first embodiment indicate structural elements thatare the same, and preceding explanations thereof are referenced.

In the electric work machine system 1 according to the above-describedfirst embodiment, the diode D11 is provided in the signal path 26 of thebattery pack 10 and the diode D31 is provided in the signal path 46 ofthe electric work machine 30.

In contrast thereto, in the electric work machine system 3 according tothe second embodiment, diode D72 is provided in battery pack 71 insteadof the diode D11 of the first embodiment, as shown in FIG. 3 . The diodeD72 is provided within (in series with) a data input circuit 72 in aconducting path that extends from the connection point 23 c to theconnection point 23 d via the resistor R12. Specifically, the anode ofthe diode D72 is electrically connected to the connection point 23 c,and the cathode of the diode D72 is electrically connected to the firstend of the resistor R12.

In an electric work machine 76, too, diode D77 is provided instead ofthe diode D31 of the first embodiment. The diode D77 is provided within(in series with) a data input circuit 77 in a conducting path thatextends from the connection point 43 c to the connection point 43 d viathe resistor R32. Specifically, the anode of the diode D77 iselectrically connected to the connection point 43 c, and the cathode ofthe diode D77 is electrically connected to the first end of the resistorR32.

In the above-described electric work machine system 3 according to thesecond embodiment, any noise currents generated (arising) within theclosed loop are limited (at least partially blocked, truncated, reduced,diminished or the like) by the diode D72 and the diode D77. Moreover, inthe battery pack 71, the diode D72 is provided in a path that isseparate from the path extending from the communication terminal 13 tothe gate of the switching device T11. Consequently, as compared to theelectric work machine system 3 of the above-described first embodiment,the electric potential differential (i.e., the voltage drop) between thecommunication terminal 13 and the gate of the switching device T11during reception of the equipment transmit-data is reduced. That is,because the diode D11 is provided between the gate of the switchingdevice T11 and the communication terminal 13 in the first embodiment,the diode D11 will cause a voltage drop in the signal being transmittedfrom the communication terminal 13 to the gate of the switching deviceT11. Owing to the different location of the diode D72 of the secondembodiment, it does not cause such a voltage drop at the gate of theswitching device T11.

It is noted that, in the charger 50 shown in FIG. 2 , too, the diode D51for limiting (reducing, diminishing) noise currents within the closedloop may be disposed the same as the diode D77 in the electric workmachine 76 shown in FIG. 3 . That is, in the charger 50 shown in FIG. 2, a diode may be provided, instead of the diode D51, between theconnection point 63 c and the first end of the resistor R52.

3. Third Embodiment

An electric work machine system 4 according to a third embodiment willnow be explained, with reference to FIG. 4 . Because the basicconfiguration of the electric work machine system 4 according to thethird embodiment is the same as that of the electric work machine system1 according to the first embodiment, only those points of differencefrom the electric work machine system 1 will be explained below. It isnoted that symbols in the third embodiment that are the same as those inthe first embodiment indicate structural elements that are the same, andpreceding explanations thereof will be referenced.

In the electric work machine system 4 according to the third embodiment,diode D82 is provided in battery pack 81 instead of the diode D11 of thefirst embodiment, as shown in FIG. 4 . The diode D82 is provided withina data input circuit 82 between the connection point 23 d and the groundterminal 23 b. Specifically, the anode of the diode D82 is electricallyconnected to the connection point 23 d, and the cathode of the diode D82is electrically connected to the ground terminal 23 b.

In electric work machine 86, too, diode D87 is provided instead of thediode D31 of the first embodiment. The diode D87 is provided within adata input circuit 87 between the connection point 43 d and the groundterminal 43 b. Specifically, the anode of the diode D87 is electricallyconnected to the connection point 43 d, and the cathode of the diode D87is electrically connected to the ground terminal 43 b.

Both the diode D82 and the diode D87 may be, e.g., Schottky barrierdiodes (or simply, “Schottky diodes”) in the third embodiment. Theprinciple reasons for using Schottky barrier diodes as the diode D82 andthe diode D87 are as follows. That is, in the battery pack 81, if theswitching device T11 turns ON in response to the equipment transmit-datafrom the electric work machine 86, then, in the battery control circuit20, it should be determined that the value of the voltage input to theRx terminal 20 b is at the L level. However, owing to the magnitude ofthe forward voltage of the diode D82, there is a possibility that thevalue of the voltage input to the Rx terminal 20 b will become high andnot be determined to be at the L level in the battery control circuit20. In the electric work machine 86, too, if the switching device T31has turned ON, then there is a possibility that, owing to the magnitudeof the forward voltage of the diode D87, the value of the voltage inputto the Rx terminal 40 b will not correctly be determined in the drivecontrol circuit 40 to be at the L level.

Accordingly, in the third embodiment, Schottky barrier diodes, whichhave a lower forward voltage, are used as the diodes D82, D87. However,the diodes D82, D87 may be some other type of diodes that differs fromSchottky barrier diodes.

In the above-described electric work machine system 4 according to thethird embodiment, any noise currents generated (arising) within theclosed loop are limited (reduced, diminished, etc.) by the diode D82 andthe diode D87.

It is noted that, in the charger 50 shown in FIG. 2 , too, the diode D51for limiting noise currents within the closed loop may be disposed thesame as the diode D87 in the electric work machine 86 shown in FIG. 4 .That is, in the charger 50 shown in FIG. 2 , a diode may be provided,instead of the diode D51, between the connection point 63 d and theground terminal 63 b. This diode also may be, for example, a Schottkybarrier diode.

4. Fourth Embodiment

An electric work machine system 5 according to a fourth embodiment willnow be explained, with reference to FIG. 5 . The electric work machinesystem 5 shown in FIG. 5 comprises the battery pack 10, the electricwork machine 30, and an intermediate device 100. The battery pack 10 andthe electric work machine 30 are the same as the battery pack 10 and theelectric work machine 30 according to the first embodiment as shown inFIG. 1 . The intermediate device 100 also may be called, e.g., a remoteadapter, a remote battery adapter, an umbilical battery adapter, aremote battery pod adapter or a corded battery-tool adapter.

The intermediate device 100 provides an electrical connection and aphysical connection between the battery pack 10 and the electric workmachine 30. The intermediate device 100 comprises a first mounting part101, a second mounting part 102, and a cable 103. The first mountingpart 101 is provided on a first end of the cable 103 and isadapted/configured such that the battery pack 10 is mountable thereonand demountable therefrom. The second mounting part 102 is provided on asecond end of the cable 103 and is adapted/configured such that theelectric work machine 30 is mountable thereon and demountable therefrom.The cable 103 is flexible. The cable 103 may have a length of, e.g., 1meter, 2 meters, 3 meters, etc. or any length between 1-3 meters.

The first mounting part 101 comprises a first positive electrodeintermediate terminal 111, a first negative electrode intermediateterminal 112, and a first communication intermediate terminal 113. Whenthe battery pack 10 is mounted on (physically connected to) the firstmounting part 101, the positive electrode terminal 11 of the batterypack 10 is electrically connected to the first positive electrodeintermediate terminal 111, the negative electrode terminal 12 of thebattery pack 10 is electrically connected to the first negativeelectrode intermediate terminal 112, and the communication terminal 13of the battery pack 10 is electrically connected to the firstcommunication intermediate terminal 113. The first mounting part 101optionally may also include, e.g., a hook, a clip or other type offastening device (not shown) that enables the first mounting part 101(with the battery pack 10 mounted thereon) to be attached, e.g., to auser's belt, shoulder harness or other article of clothing or to aphysical structure, such as a ladder. In the alternative, such afastening device may be provided directly on the battery pack 10 or maybe removably attachable to the battery pack 10.

The second mounting part 102 comprises a second positive electrodeintermediate terminal 121, a second negative electrode intermediateterminal 122, and a second communication intermediate terminal 123. Whenthe electric work machine 30 is mounted on (physically connected to) thesecond mounting part 102, the positive electrode terminal 31 of theelectric work machine 30 is electrically connected to the secondpositive electrode intermediate terminal 121, the negative electrodeterminal 32 of the electric work machine 30 is electrically connected tothe second negative electrode intermediate terminal 122, and thecommunication terminal 33 of the electric work machine 30 iselectrically connected to the second communication intermediate terminal123.

The cable 103 comprises a positive electrode intermediate wire 106, anegative electrode intermediate wire 107, and a communicationintermediate wire 108. The positive electrode intermediate wire 106electrically connects the first positive electrode intermediate terminal111 and the second positive electrode intermediate terminal 121. Thenegative electrode intermediate wire 107 electrically connects the firstnegative electrode intermediate terminal 112 and the second negativeelectrode intermediate terminal 122. The communication intermediate wire108 electrically connects the first communication intermediate terminal113 and the second communication intermediate terminal 123.

The above-described electric work machine system 5 makes it possible touse the electric work machine 30 while the electric work machine 30 isspaced apart from the battery pack 10, e.g., by one meter or more.Consequently, it becomes possible to provide an ergonomic electric workmachine system 5, especially for applications in which the user has tohold the electric work machine 30, e.g., above the user's head for anextended period of time.

It is noted that the second mounting part 102 may be mounted on anddemounted from the charger 50 shown in FIG. 2 . That is, the batterypack 10 and the charger 50 also may be connectable to one another usingthe intermediate device 100.

5. Other Embodiments

Although embodiments of the present disclosure were explained above, thepresent disclosure is not limited to the embodiments described above,and it is understood that various modifications may be effected.

(5-1) In the battery pack, a limiting circuit for achieving theabove-described noise current limiting function may be provided at alocation different from that of the diode D11 (refer to FIG. 1 ), thediode D72 (refer to FIG. 3 ), and the diode D82 (refer to FIG. 4 )described in the above mentioned embodiments.

For example, in the battery pack 10 shown in FIG. 1 , a limiting circuitmay be provided, instead of the diode D11, within the data input circuit23 in the conducting path between the input terminal 23 a and theconnection point 23 c (i.e., in the conducting path in which theresistor R11 is provided). More specifically, for example, a limitingcircuit may be provided that comprises a diode whose anode iselectrically connected to the input terminal 23 a and whose cathode iselectrically connected to the first end of the resistor R11. Inaddition, for example, a limiting circuit may be provided that comprisesa diode whose anode is electrically connected to the second end of theresistor R11 and whose cathode is electrically connected to theconnection point 23 c.

In addition, for example, in the battery pack 71 shown in FIG. 3 , alimiting circuit may be provided, instead of the diode D72, in theconducting path between the resistor R12 and the connection point 23 d.More specifically, for example, a limiting circuit may be provided thatcomprises a diode whose anode is electrically connected to the secondend of the resistor R12 and whose cathode is electrically connected tothe connection point 23 d.

In addition, for example, in the battery pack 81 shown in FIG. 4 , alimiting circuit may be provided, instead of the diode D82, in theconducting path extending from the ground terminal 23 b of the datainput circuit 82 to the ground line 15. More specifically, for example,a limiting circuit may be provided that comprises a diode whose anode iselectrically connected to the ground terminal 23 b and whose cathode iselectrically connected to the ground line 15.

(5-2) The same as the limiting circuit in the battery pack described in(5-1) above, the limiting circuit in the electric work machine and thelimiting circuit in the charger likewise may be provided at locationsthat differ from the locations described in the above mentionedembodiments.

(5-3) The limiting circuit in the battery pack may differ from thelimiting circuit in the connected equipment, which is connected to thebattery pack.

(5-4) The location of the limiting circuit in the battery pack maydiffer from the location of the limiting circuit in the connectedequipment, which is connected to the battery pack. Specifically, forexample, in the electric work machine system 1 shown in FIG. 1 , thelocation of the diode D11 in the battery pack 10 may be the same asshown in FIG. 1 , while, in the electric work machine 30, the limitingcircuit may be provided, instead of the diode D31, at a locationseparate/different from that of the diode D31. Conversely, the locationof the diode D31 in the electric work machine 30 may be the same asshown in FIG. 1 , while, in the battery pack 10, the limiting circuitmay be provided, instead of the diode D11, at a locationseparate/different from that of the diode D11. This applies likewise tothe charging system 2 shown in FIG. 2 and to the electric work machinesystems 3, 4 shown in FIG. 3 and FIG. 4 .

(5-5) The limiting circuit of the present disclosure may differ from acircuit that comprises a single diode, as described in the embodimentsabove. Limiting circuits of the present disclosure may be constitutedwithout containing a diode to achieve the noise current limitingfunction described above by using a component or components or a circuitthat differ from a diode. More specifically, the limiting circuit of thepresent disclosure may be, e.g., a reverse current protection circuitthat reduces or diminishes the influence of currents (noise) flowing inthe direction opposite to the transmitted signals. Most diodes, inprinciple, exhibit reverse current leakage. Therefore, diodes, such asSchottky diodes, will permit some reverse current (noise) to passthrough. However, if the noise is sufficiently attenuated, the signalintegrity of the signal moving in the opposite direction is notcritically affected (i.e. the receiver of the signal can stillaccurately discern whether the signal is H level (high) or L level(low)). Therefore, it is not necessary to entirely block the noisecurrent flowing in the reverse direction to the signal; it is onlynecessary to sufficiently attenuate the noise current so that it doesnot unduly influence/affect the signal integrity. Therefore, a varietyof types of reverse (noise) current protection circuit that achieve orrealize this noise reducing effect/function or even a noise eliminatingeffect/function may be suitably utilized with the present teachings.

(5-6) The present teachings may be applied to a variety of electric workmachines, such as, for example: power tools for masonry, metalworking,and carpentry; work machines for gardening (e.g., outdoor powerequipment); apparatuses prepared for work site environments; all ofwhich are used at work sites such as professional or DIY carpentry,manufacturing, gardening, and construction. More specifically, thepresent teachings may be applied to a variety of electric work machinessuch as, for example, power hammers, power hammer drills, power drills,power drivers, power wrenches, power grinders, power circular saws,power reciprocating saws, power jigsaws, power cutters, power chainsaws,power planers, power nailers (including rivet tools), power hedgetrimmers, power lawnmowers, power lawn clippers, power brush cutters,power cleaners, power blowers, power sprayers, power spreaders, powerdust collectors or the like.

(5-7) A plurality of functions having a single constituent element inthe embodiments above may be implemented by a plurality of constituentelements, and a single function having a single constituent element maybe implemented by a plurality of constituent elements. In addition, aplurality of functions having a plurality of constituent elements may beimplemented by a single constituent element, and a single functionimplemented by a plurality of constituent elements may be implemented bya single constituent element. In addition, a portion of theconfiguration of each embodiment above may be omitted. In addition, atleast a portion of the configuration of each embodiment above may besupplemented or substituted by the configuration of other embodimentsabove.

Representative, non-limiting examples of the present invention weredescribed above in detail with reference to the attached drawings. Thisdetailed description is merely intended to teach a person of skill inthe art further details for practicing preferred aspects of the presentteachings and is not intended to limit the scope of the invention.Furthermore, each of the additional features and teachings disclosedabove may be utilized separately or in conjunction with other featuresand teachings to provide improved battery-connected (battery-powered)systems, electric work machines (e.g., power tools, outdoor powerequipment, etc.), battery packs and chargers.

Moreover, combinations of features and steps disclosed in the abovedetailed description may not be necessary to practice the invention inthe broadest sense, and are instead taught merely to particularlydescribe representative examples of the invention. Furthermore, variousfeatures of the above-described representative examples, as well as thevarious independent and dependent claims below, may be combined in waysthat are not specifically and explicitly enumerated in order to provideadditional useful embodiments of the present teachings.

All features disclosed in the description and/or the claims are intendedto be disclosed separately and independently from each other for thepurpose of original written disclosure, as well as for the purpose ofrestricting the claimed subject matter, independent of the compositionsof the features in the embodiments and/or the claims. In addition, allvalue ranges or indications of groups of entities are intended todisclose every possible intermediate value or intermediate entity forthe purpose of original written disclosure, as well as for the purposeof restricting the claimed subject matter.

Additional embodiments of the present teachings include, but are notlimited to:

An electric work machine configured to receive electric power from abattery pack comprising a battery, the electric work machine comprising:

-   -   a first positive electrode terminal configured to be        electrically connected to a second positive electrode terminal        of the battery pack;    -   a first negative electrode terminal configured to be        electrically connected to a second negative electrode terminal        of the battery pack;    -   a first communication terminal configured to be electrically        connected to a second communication terminal of the battery        pack;    -   a data output circuit comprising an output terminal connected to        the first communication terminal, the data output circuit being        configured to generate and output a first signal via the output        terminal;    -   a data input circuit comprising an input terminal connected to        the first communication terminal, and a ground terminal        connected to the first negative electrode terminal, the data        input circuit being configured to receive a second signal output        from the second communication terminal of the battery pack via        the first communication terminal and the input terminal;    -   a limiting circuit configured to at least limit a flow of        electric current in a direction from the first negative        electrode terminal to the first communication terminal via the        data input circuit;    -   a manipulatable switch configured to be manipulated by a user of        the electric work machine;    -   a motor;    -   a motor drive circuit configured to drive the motor, using        electric power supplied from the battery pack via the first        positive electrode terminal and the first negative electrode        terminal, in accordance with manipulation of the manipulatable        switch; and    -   a drive mechanism configured to mount or hold a work output        member and configured to cause the work output member to act on        a work target by transmitting a rotational drive force of the        motor and driving the work output member using that rotational        drive force.

A charger configured to charge a battery pack comprising a battery, thecharger comprising:

-   -   a first positive electrode terminal configured to be        electrically connected to a second positive electrode terminal        of the battery pack;    -   a first negative electrode terminal configured to be        electrically connected to a second negative electrode terminal        of the battery pack;    -   a first communication terminal configured to be electrically        connected to a second communication terminal of the battery        pack;    -   a data output circuit comprising an output terminal connected to        the first communication terminal, the data output circuit being        configured to generate and output a first signal via the output        terminal;    -   a data input circuit comprising an input terminal connected to        the first communication terminal, and a ground terminal        connected to the first negative electrode terminal, the data        input circuit being configured to receive a second signal from        the second communication terminal of the battery pack via the        first communication terminal and the input terminal;    -   a limiting circuit configured to at least limit a flow of        electric current in a direction from the first negative        electrode terminal to the first communication terminal via the        data input circuit; and    -   a charging circuit configured to output an electric current for        charging the battery of the battery pack via the first positive        electrode terminal and the first negative electrode terminal.

EXPLANATION OF THE REFERENCE NUMBERS

-   -   1, 3, 4, 5 Electric work machine system    -   2 Charging system    -   10, 71, 81 Battery pack    -   11, 31, 51 Positive electrode terminals    -   12, 32, 52 Negative electrode terminals    -   13, 33, 53 Communication terminals    -   14 Battery    -   15, 35, 55 Ground lines    -   23, 43, 63, 72, 77, 82, 87 Data input circuits    -   23 a, 43 a, 63 a Input terminals    -   23 b, 43 b, 63 b Ground terminals    -   24, 44, 64 Data output circuits    -   24 a, 44 a, 64 a Output terminals    -   26, 46, 66 Signal paths    -   26 a, 46 a, 66 a Connection points    -   30, 76, 86 Electric work machine    -   34 Motor    -   36 Manipulatable switch    -   37 Drive mechanism    -   38 Work output member    -   39, 59 Mounting part    -   45 Motor drive circuit    -   50 Charger    -   100 Intermediate device    -   101 First mounting part    -   102 Second mounting part    -   103 Cable    -   106 Positive electrode intermediate wire    -   107 Negative electrode intermediate wire    -   108 Communication intermediate wire    -   111 First positive electrode intermediate terminal    -   112 First negative electrode intermediate terminal    -   113 First communication intermediate terminal    -   121 Second positive electrode intermediate terminal    -   122 Second negative electrode intermediate terminal    -   123 Second communication intermediate terminal    -   D11, D31, D51, D72, D77, D82, D87 Diodes    -   T11, T31, T51 Switching devices

1.-18. (canceled)
 19. A charger comprising: a first positive electrodeterminal configured to be electrically coupled to a second positiveelectrode terminal of a battery pack; a first negative electrodeterminal configured to be electrically coupled to a second negativeelectrode terminal of the battery pack; a first communication terminal;a charging circuit configured to supply electric power to the batterypack via the first positive electrode terminal and the first negativeelectrode terminal; a data input circuit including an input terminalelectrically coupled to the first communication terminal and a groundterminal electrically coupled to the first negative electrode terminal,the data input circuit being configured to receive first data via thefirst communication terminal and the input terminal, and a limitingcircuit configured to limit a flow of electric current from the firstnegative electrode terminal to the first communication terminal via thedata input circuit to a greater degree than a flow of electric currentfrom the first communication terminal to the first negative electrodeterminal via the data input circuit.
 20. The charger according to claim19, wherein the first communication terminal is configured (i) to beelectrically coupled to a second communication terminal on the batterypack and (ii) to receive the first data from the battery pack via thesecond communication terminal.
 21. The charger according to claim 19,further comprising a data output circuit including an output terminalelectrically coupled to the first communication terminal, wherein thedata output circuit is configured (i) to generate second data and (ii)to output the second data via the output terminal.
 22. The chargeraccording to claim 21, further comprising a signal path electricallycoupling the first communication terminal and the input terminal, thesignal path including a connection point, wherein: the output terminalis electrically coupled to the connection point and thereby to the firstcommunication terminal via the signal path; and the limiting circuit iselectrically coupled to an electric current path extending from theconnection point through the data input circuit to the first negativeelectrode terminal.
 23. The charger according to claim 19, wherein: thedata input circuit includes: a switching device having a first switchterminal electrically coupled to the input terminal and a second switchterminal electrically coupled to the ground terminal; a bias pathelectrically coupling the first switch terminal and the second switchterminal; and a resistor in the bias path; and the limiting circuit isin the bias path.
 24. The charger according to claim 19, wherein thelimiting circuit includes a diode configured to limit the flow of theelectric current from the first negative electrode terminal to the firstcommunication terminal via the data input circuit.
 25. The chargeraccording to claim 21, wherein: the input terminal is electricallycoupled to the output terminal; and the data input circuit is configuredto receive the second data output by the data output circuit via theinput terminal.
 26. The charger according to claim 19, wherein thelimiting circuit has asymmetric conductance.
 27. The charger accordingto claim 26, wherein the limiting circuit is electrically coupled inseries with an electric current path extending from the firstcommunication terminal through the data input circuit to the firstnegative electrode terminal.
 28. The charger according to claim 22,wherein the limiting circuit is electrically coupled to the connectionpoint and to the input terminal.
 29. The charger according to claim 19,wherein: the data input circuit includes: a switching device having afirst switch terminal electrically coupled to the input terminal, and asecond switch terminal electrically coupled to the ground terminal; anda signal path electrically coupling the second switch terminal to theground terminal; and the limiting circuit is in the signal path.
 30. Thecharger according to claim 21, further comprising a communicationcircuit that (i) includes the data input circuit and the data outputcircuit, and (ii) is configured to perform half duplex serialcommunication with the battery pack via the first communicationterminal.
 31. A method comprising: electrically coupling a firstnegative electrode terminal of a first electric device with a secondnegative electrode terminal of a second electric device, the firstelectric device being a charger, a battery pack, or an electric powertool, the second electric device being distinct from the first electricdevice; and limiting a flow of electric current from the first negativeelectrode terminal to a communication terminal of the first electricdevice via a data input circuit of the first electric device to agreater degree than a flow of electric current from the communicationterminal to the first negative electrode terminal via the data inputcircuit.
 32. The method according to claim 31, wherein limiting a flowof electric current from the first negative electrode terminal to acommunication terminal of the first electric device via a data inputcircuit of the first electric device to a greater degree than a flow ofelectric current from the communication terminal to the first negativeelectrode terminal via the data input circuit is performed based on: (i)the first negative electrode terminal being electrically coupled withthe second negative electrode terminal; and/or (ii) an electric currentflowing between the first negative electrode terminal and the secondnegative electrode terminal.